Preparation, structure and properties of octenylsuccinic anhydride modified starch

Doctor of PhilosophyDepartment of Grain Science and IndustryYong Cheng ShiThe reaction of starch and octenylsuccinic anhydride (OSA) produces lipophilic starch that has the ability to stabilize oil-in-water emulsions. The functional properties of octenylsuccinate (OS) starch depend on its molecular structure and distribution of OS groups. Structures of OSA and OS starches were investigated by NMR spectroscopy. In granular OS starches, OS groups were substituted at O-2, O-3 positions, but not the O-6 position. Distribution of OS groups was investigated by enzyme hydrolysis followed by chromatography analysis. OS substitution predominantly occurred at the amorphous region of the starch granules. OS starch of degree of substitution (DS) 0.018 had OS groups located close to the branching points, whereas the OS substitution in OS starch of DS 0.092 occurred near non-reducing ends as well as the branching points. OS starches with different substitution patterns were prepared from two approaches. OS starches from the first approach had OS substitution near the branching points or non-reducing ends, whereas OS starches from the second approach had OS groups distributed randomly throughout the starch chains. A method of preparing OS starch by dry heating a mixture of waxy maize starch and OSA was developed. The optimum reaction was investigated and found to be pH 8.5 by addition of 3% NH4HCO3, 180 °C and 2 h. Reaction efficiency of ca. 90% was obtained at OSA levels from 1 to 6%. The OS starch had a DS of 0.0202 with 98% solubility when reacted with 3% OSA. Transglucosidation occurred during the reaction. The OS starch had a degree of branching of 19.8 %. The highly debranched OS starch showed excellent emulsification property for vitamin E and vitamin A. The structural changes of insoluble native waxy maize starch granules to cold watersoluble pyrodextrin during dextrinization under acidic conditions were investigated. We proposed that the starch was hydrolyzed by acid in the amorphous regions. Unwinding of the double helices also occurred, and crystallite size decreased. Starch molecules were hydrolyzed into small molecule fractions but remain in a radial arrangement. Glycosyl linkages including - (1 2), -(1 6), -(1 2), and -(1 6) linkages were formed and the majority starch chain terminals were 1,6-anhydro- -D- lucopyranose. Transglucosidation occurred during dextrinization and the resulted pyrodextrin was highly branched

A New Screening Evaluation Method for Carbon Dioxide Miscible Flooding Candidate Reservoirs

Prior to the implementation of CO2 injection EOR projects, the screening evaluation of candidate reservoirs will promote the economic benefits of CO2 injection. Currently, a uniform screening method for CO2 miscible flooding does not exist. Based on more than 112 successfully implemented CO2 miscible flooding reservoirs, which was referred in 2010 Worldwide EOR Survey, and CO2 miscible flooding mechanisms, this paper picks out 12 reservoir and fluid parameters affecting CO2 miscible flooding results as comprehensive evaluation parameters for screening candidate reservoirs. According to investigations on a large number of domestic and international CO2 miscible flooding projects, the quantitative methods are determined by theoretical analyses, field experience, and probability statistics. By means of calculating the combinational weights by improved analytical hierarchy process (AHP) and entropy method and combining the advantages of technique for order preference by similarity to ideal solution (TOPSIS) with gray relational analysis to construct a new similarity nearness degree, the weighted GC-TOPSIS model is established for screening candidate reservoirs. This screening method was employed for the assessment of five classical candidate reservoirs proposed for CO2 miscible flooding. The results show that this new method can correctly evaluate and compare the potential of CO2 miscible flooding.</span

Disparities and risks of sexually transmissible infections among men who have sex with men in China: a meta-analysis and data synthesis.

BACKGROUND: Sexually transmitted infections (STIs), including Hepatitis B and C virus, are emerging public health risks in China, especially among men who have sex with men (MSM). This study aims to assess the magnitude and risks of STIs among Chinese MSM. METHODS: Chinese and English peer-reviewed articles were searched in five electronic databases from January 2000 to February 2013. Pooled prevalence estimates for each STI infection were calculated using meta-analysis. Infection risks of STIs in MSM, HIV-positive MSM and male sex workers (MSW) were obtained. This review followed the PRISMA guidelines and was registered in PROSPERO. RESULTS: Eighty-eight articles (11 in English and 77 in Chinese) investigating 35,203 MSM in 28 provinces were included in this review. The prevalence levels of STIs among MSM were 6.3% (95% CI: 3.5-11.0%) for chlamydia, 1.5% (0.7-2.9%) for genital wart, 1.9% (1.3-2.7%) for gonorrhoea, 8.9% (7.8-10.2%) for hepatitis B (HBV), 1.2% (1.0-1.6%) for hepatitis C (HCV), 66.3% (57.4-74.1%) for human papillomavirus (HPV), 10.6% (6.2-17.6%) for herpes simplex virus (HSV-2) and 4.3% (3.2-5.8%) for Ureaplasma urealyticum. HIV-positive MSM have consistently higher odds of all these infections than the broader MSM population. As a subgroup of MSM, MSW were 2.5 (1.4-4.7), 5.7 (2.7-12.3), and 2.2 (1.4-3.7) times more likely to be infected with chlamydia, gonorrhoea and HCV than the broader MSM population, respectively. CONCLUSION: Prevalence levels of STIs among MSW were significantly higher than the broader MSM population. Co-infection of HIV and STIs were prevalent among Chinese MSM. Integration of HIV and STIs healthcare and surveillance systems is essential in providing effective HIV/STIs preventive measures and treatments. TRIAL REGISTRATION: PROSPERO NO: CRD42013003721

Preparation and structure of Octenyl succinic anhydride modified waxy maize starch, microporous starch and maltodextrin

Master of ScienceDepartment of Grain Science and IndustryYong Cheng ShiOctenyl succinic anhydride (OSA) modified starch is widely used in emulsion and encapsulation applications. The functionality of OS starch depends on its molecular structure. A systematic study was performed to investigate the reaction of OSA with granular waxy maize (WM) starch, microporous WM starch and soluble maltodextrin. OS starches were prepared in an aqueous slurry system, and the degree of substitution (DS) of OS starches was determined by titration and [superscript]1H-NMR spectroscopy. For both 3% and 50% OSA treatment, OS maltodextrin had higher DS and reaction efficiency (RE) than OSA modified WM starch and microporous WM starch. The maximum DS of OSA modified granular WM starch was 0.14 and the highest DS of OS maltodextrin was 0.27. For the 3% OSA treatment, the RE for WM starch and maltodextrin was ~ 80% and ~100%, respectively. The structure of OSA modified WM starch and the locations of OS groups on anhydroglucose units (AGUs) were studied by [superscript]1H-NMR and [superscript]13C-NMR. As increasing OS substitution, [superscript]13C - signal at C-1 shifted to upper field. In addition, the [superscript]13C - signal at C-6 shifted to downfield when DS reached 0.073. The results suggested that OS groups were predominantly substituted at the O-2 position and started being substituted at O-6 position when DS was 0.073. FT-IR microspectroscopy was used to detect the heterogeneity OS starch products. Native WM starch, OSA modified WM starches (DS=0.019 and 0.073) and a starch blend with native starch to OSA modified WM starch (DS=0.073) ratio of 7:3 were examined. More than one hundred starch granules of each sample were analyzed one by one by FT-IR microspectroscopy. For the OS starch (DS=0.019), 7% starch granules showed carbonyl absorption. For the OS starch (DS=0.073), 99% starch granules showed carbonyl absorption but the intensity varied, indicating that OSA reacted with most starch granules when DS was 0.073. However, the OS contents of individual granules varied. For the starch blend, only 30% starch granules had carbonyl absorption. FT-IR microspectroscopy is a useful tool to detect heterogeneity of OS starch blends containing native starch

Journal of Petroleum Science and Technology *Corresponding author A New Screening Evaluation Method for Carbon Dioxide Miscible Flooding Candidate Reservoirs

ABSTRACT Prior to the implementation of CO 2 injection EOR projects, the screening evaluation of candidate reservoirs will promote the economic benefits of CO 2 injection. Currently, a uniform screening method for CO 2 miscible flooding does not exist. Based on more than 112 successfully implemented CO 2 miscible flooding reservoirs, which was referred in 2010 Worldwide EOR Survey, and CO 2 miscible flooding mechanisms, this paper picks out 12 reservoir and fluid parameters affecting CO 2 miscible flooding results as comprehensive evaluation parameters for screening candidate reservoirs. According to investigations on a large number of domestic and international CO 2 miscible flooding projects, the quantitative methods are determined by theoretical analyses, field experience, and probability statistics. By means of calculating the combinational weights by improved analytical hierarchy process (AHP) and entropy method and combining the advantages of technique for order preference by similarity to ideal solution (TOPSIS) with gray relational analysis to construct a new similarity nearness degree, the weighted GC-TOPSIS model is established for screening candidate reservoirs. This screening method was employed for the assessment of five classical candidate reservoirs proposed for CO 2 miscible flooding. The results show that this new method can correctly evaluate and compare the potential of CO 2 miscible flooding

Obstacle Avoidance Algorithm for 7-DOF Redundant Anthropomorphic Arm

To deal with the problem of obstacle avoidance for redundant robots, an obstacle avoidance algorithm based on the internal motion of the 7-DOF redundant anthropomorphic arm is presented. The motion of that critical points move away from the closest points on the obstacles is defined as obstacle avoiding motion. Two transitioning variables were used to make a smooth, continuous transition between the primary and the secondary tasks. Using this approach, the robot can get the target configuration while avoiding the obstacles. Finally, the validity of the obstacle avoidance algorithm based on transitioning between tasks is manifested by simulation. The results show that, for the obstacle avoiding problem, the redundant robot not only can realize the obstacle avoidance, but also prevents the conflict between tasks by the proposed approach

Obstacle Avoidance Algorithm for 7-DOF Redundant Anthropomorphic Arm

To deal with the problem of obstacle avoidance for redundant robots, an obstacle avoidance algorithm based on the internal motion of the 7-DOF redundant anthropomorphic arm is presented. The motion of that critical points move away from the closest points on the obstacles is defined as obstacle avoiding motion. Two transitioning variables were used to make a smooth, continuous transition between the primary and the secondary tasks. Using this approach, the robot can get the target configuration while avoiding the obstacles. Finally, the validity of the obstacle avoidance algorithm based on transitioning between tasks is manifested by simulation. The results show that, for the obstacle avoiding problem, the redundant robot not only can realize the obstacle avoidance, but also prevents the conflict between tasks by the proposed approach

Effect of Different Temperatures on the Hydration Kinetics of Urea-Doped Cement Pastes

Urea can solve the problem of concrete cracking due to temperature stress. However, its effect is affected by temperature. The influencing mechanism of temperature on urea-doped cement pastes is still unclear. This paper explores the effect of different temperatures on the hydration kinetics of urea-doped cement pastes. The isothermal calorimeter (TAM Air) was used to test hydration at three constant temperatures (20 °C, 40 °C, and 60 °C). The effects of the urea admixture and temperature on the hydration process and hydration kinetics parameters were investigated. The hydration mechanism was analyzed, and the changes in macroscopic mechanical compressive strength and porosity were tested. The results show that, as the urea content (UC) increases, the rate of hydration gradually decreases, and the increase in temperature promotes the inhibitory effect of urea. At 60 °C, UC of 8% can be reduced by 23.5% compared with the pure cement (PC) group’s hydration rate. As the temperature increases from 20 °C to 60 °C, the Krstulovic–Dabic model changes from the NG-I-D process to the NG-D process. The effect of urea on the compressive strength of the cement is mainly shown in the early stage, and its effect on later strength is not obvious. In addition, urea will increase its early porosity. The porosity will gradually decrease in the later stage. The results of the study clarify the effect of temperature on urea-doped cement pastes. The optimal content of urea in cement is about 8%, which will provide theoretical guidance for solving the cracking problem of large-volume concrete due to temperature stress